Doepfer A-137-1 Wave Multiplier I

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Wave multiplier

A-137-1 is a voltage controlled waveform multiplier. The basic idea of a wave multiplier is to multiply the waveform of an incoming audio signal (e.g. triangle/sinus/sawtooth of a VCO) within one period. This creates additional harmonics in the audio signal. The period duration and thus also the pitch of the signal remain unchanged - in contrast to frequency multiplication such as with the PLL module A-196.

The A-137-1 works as an "inverse low-pass filter", i.e. it adds additional harmonics to a signal poor in overtones, whereas a low-pass filter (e.g. A-120) filters out overtones from a signal rich in overtones. Therefore, the A-137 gives the best results in combination with comparatively low harmonic waveforms (e.g. triangle, sine) as input signal. For overtone-rich input signals (e.g. sawtooth) the A-137 can also be used, but the effect is not as spectacular as with a triangle signal. With square-wave signals, the effect of the A-137 is hardly noticeable.

The Multiples parameter (adjustable manually and by control voltage) defines the number of waveform multiplications within a period. The two parameters Folding Level and Symmetry (both adjustable manually and by control voltage) set the upper and lower level at which the convolution of the signal takes place. The function of these two parameters is shown graphically in the diagram below. The Harmonics parameter (adjustable manually and by control voltage) adds further harmonics (i.e. in addition to the harmonics created by waveform multiplication) by sharpening the waveform edges (amplification and limiting) and adding overshoot peaks (attenuated waves at the edges).

  • Input Level to adjust different input levels for the optimal effect of the module
  • Multiples: Number of curve multiplications, manual setting
  • Harmonics: Adding additional harmonics by an effect similar to the resonance of filters, manual adjustment
  • Folding Level: Value of the upper and lower folding level, for explanation see sketch below, manual setting
  • Symmetry: Symmetry of upper and lower convolution level, see sketch below for explanation, manual adjustment
  • Width: 14 TE / HP
  • Depth: 65 mm
  • Current consumption: +40 mA (+12 V) / -20 mA (-12 V)

Inputs/outputs:

  • Audio In - also suitable for control voltages
  • Multiples CV In: Control voltage input for the number of curve multiplications, with attenuator
  • Harmonics CV In: Control voltage input for the Harmonics parameter, with attenuator
  • Folding Level CV In: Control voltage input for the convolution level, with attenuator
  • Symmetry CV In: Control voltage input for convolutional symmetry, with attenuator
  • Audio Out: Output for the processed audio or control signal.
Available since October 2004
Item number 173990
Sales Unit 1 piece(s)
Width 14 TE / HP
1.725 kr
Including VAT; Excluding kr200 shipping
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20 Customer ratings

4.9 / 5

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11 Reviews

G
Very versatile wavefolder!
Grent 20.06.2013
Everyone needs a wavefolder. It took me some time to properly grasp this module, but now it makes it's way into almost every patch I make. You can get a huge range of sounds! It's best fed with a triangle or sine as the wave folding circuit adds lots of harmonics to the signal. Adding some slow modulations to the "symmetry" and "harmonics" inputs can create an ever changing sound that never sounds the same twice!

A great tip I learned with this is to keep the input level down low, it is easy to overdrive, and by doing that you may miss the subtle morphing waveshapes that this module excels so well at.

A small issue I have with this is the depth, it's a little bit deeper than most modules so it may have trouble fitting in a shallow case. (No problem using any of Doepfer's excellent racks though!)

I don't think there is another wavefolder that sounds like this. One of Mr Doepfers most unique creations.
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Awesome
spewie 23.08.2020
This really is some unadulterated wave multiplying/folding action. The A-137 is not subtle and really is unapologetic about what is it's purpose. That in itself is why this thing is so devastating and awesome.
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s
great piece
squiz 07.07.2022
cool module but since the board comes out of the back distally the module did not fit in the case. check your racking system for space before you buy
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JV
as good as twice more expensive wave folders
Jean-Claude Van Damme 11.03.2022
This is one of the best sounding modules from Doepfer. I've had many wave folders, and this one sounds as good as twice more expensive ones. I believe it's more inspired by Buchla than by Serge. The controls are poorly labeled, in my opinion, but that's my only complaint.
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